1. Field of the Invention
This invention relates to prosthetic implant devices which are used in surgical procedures, and more particularly to a method and apparatus for fixation of bone during surgical procedures.
2. Description of the Related Art
During various types of surgical procedures, it is often necessary to remove and reattach a portion of bone such as a human skull. In certain neurosurgical procedures, for example, a cranial bone flap is first formed on the skull and then removed so that a surgeon can access the portions of the brain that are of concern. Such a cranial bone flap may typically be formed by drilling several burr holes through the cranial vault. After the burr holes have been drilled, osteotomies are made by a saw in the skull which connect the burr holes. The saw may typically have a guide nose which serves to avoid injuries to the dura mater. The bone flap is then removed so as to provide access to the brain. Once the procedures which are performed on the brain have been completed, the bone flap is reattached to the skull.
In craniofacial procedures, a bone segment is first formed on the skull in a manner similar to that described above and then the bone segment is removed from the skull. The bone segment is then shaped by the surgeon so as to provide the desired cosmetic appearance. Once the bone segment has been shaped in the desired manner, the bone segment is then reattached to the skull.
A variety of devices are commercially available which are used for securing a bone flap or a bone segment to the skull. For example, U.S. Pat. No. 5,210,737 discloses a device having a plurality of slots which extend radially from the center of the device. The slots are indicated as being used for forming a plurality of vanes in the device. This device, however, does not provide a high degree of flexibility with respect to placement of the bone screws which are used to secure the device to both the skull and the bone flap. Rather, the placement of the bone screws with respect to the body of the device is fixed and is determined by the specific geometry of the device. In addition, the slots which are located between the vanes of this device tend to limit the rigidity of the device. Finally, altering one or more of the vanes tends to deform the shape of the device which may cause interference at the interface between the device and both the skull and the bone flap.